Using too many em dashes and the cliché “It’s not just about X—it's about Y.” are the most obvious signs that this is definitely AI generated.
Apple devices and in particular Safari also convert regular dashes into em dashes by default unless you turn this off in Preferences.
I can confirm that — is an AI sign.
In fact, chars like “, ”, ’, and —, can be considered AI character because most humans use ", ', and -, those are the key that we all can easy find in our keyboard
And i don't understand at all why does IA loves to use —, i ask my self, where does the AI get that training from, maybe there are tons of sites with that character, but for me isn't that common at all.